The effect of a nighttime curfew on the spread of COVID-19.

While nighttime curfews are less severe restrictions compared to around-the-clock curfews in mitigating the spread of Covid-19, they are nevertheless highly controversial, with the scarce literature on their effectiveness providing mixed evidence. We study the effectiveness of the nighttime curfew in Hamburg, Germany's second largest city, in mitigating the spread of Covid-19. This curfew forbid people from leaving their home between 9 p.m. and 5 a.m. for non-essential businesses. Applying both difference-in-differences and synthetic control methods, we find that the curfew was effective in reducing the number of Covid-19 cases. As it is unclear whether and how the virus will mutate in the next time, policy-makers might have to resort to non-pharmaceutical interventions again. Nighttime curfews should be kept in the toolbox of policy-makers to fight Covid-19.